U.S. patent application number 15/522064 was filed with the patent office on 2017-11-23 for impeller and rotary machine.
This patent application is currently assigned to MITSUBISHI HEAVY INDUSTRIES, LTD.. The applicant listed for this patent is MITSUBISHI HEAVY INDUSTRIES, LTD.. Invention is credited to Atsushi MATSUO, Ryoji OKABE, Isao TOMITA, Yasunori WATANABE.
Application Number | 20170335858 15/522064 |
Document ID | / |
Family ID | 56074074 |
Filed Date | 2017-11-23 |
United States Patent
Application |
20170335858 |
Kind Code |
A1 |
OKABE; Ryoji ; et
al. |
November 23, 2017 |
IMPELLER AND ROTARY MACHINE
Abstract
This impeller is provided with: an impeller body having a
disk-like shape and rotating about an axis together with a rotating
shaft; and compressor blades (25) provided so as to protrude from
the hub surface (31b) of the impeller body, the hub surface (31b)
being formed on the front surface side of the impeller body, the
compressor blades (25) each having a pair of side surfaces (26)
which faces the circumferential direction of the rotating shaft and
along which fluid flows. Each of the compressor blades (25) is
formed in a tapered shape so that, within a range in which stress
in the direction of the axis of at least the rotating shaft is
maximum, the pair of side surfaces (26), when viewed in a
cross-section perpendicular to the axis, approach each other as the
pair of side surfaces (26) extends radially outward of the rotating
shaft.
Inventors: |
OKABE; Ryoji; (Tokyo,
JP) ; TOMITA; Isao; (Tokyo, JP) ; MATSUO;
Atsushi; (Tokyo, JP) ; WATANABE; Yasunori;
(Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MITSUBISHI HEAVY INDUSTRIES, LTD. |
Tokyo |
|
JP |
|
|
Assignee: |
MITSUBISHI HEAVY INDUSTRIES,
LTD.
Tokyo
JP
|
Family ID: |
56074074 |
Appl. No.: |
15/522064 |
Filed: |
October 8, 2015 |
PCT Filed: |
October 8, 2015 |
PCT NO: |
PCT/JP2015/078599 |
371 Date: |
April 26, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F02B 39/00 20130101;
F01D 5/048 20130101; F05D 2300/603 20130101; F04D 25/04 20130101;
F04D 29/023 20130101; F04D 29/30 20130101; F04D 29/284 20130101;
F02B 37/00 20130101 |
International
Class: |
F04D 29/30 20060101
F04D029/30; F04D 29/02 20060101 F04D029/02 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 25, 2014 |
JP |
2014-237695 |
Claims
1. An impeller comprising: an impeller body forming a disk-like
shape and rotating about an axis together with a rotating shaft;
and a plurality of blades provided so as to protrude from a hub
surface formed on a front surface side of the impeller body, the
blades each having a pair of side surfaces that faces a
circumferential direction of the rotating shaft and allows a fluid
to flow therealong, wherein each of the blades is formed such that
the pair of side surfaces in a cross-section perpendicular to the
axis approaches each other as the pair of side surfaces becomes
closer to a radial outer side of the rotating shaft, at least
within a range where stress in a direction of the axis of the
rotating shaft reaches a maximum.
2. The impeller according to claim 1, wherein the pair of side
surfaces in each of the blades is formed so as to be curved in a
concave shape in mutually approaching directions as the pair of
side surfaces becomes closer to a radial outer side and approaches
each other as the pair of side surfaces becomes closer to the
radial outer side.
3. The impeller according to claim 1, wherein each of the blades is
formed such that the pair of side surfaces in a cross-section along
the hub surface in a region close to the hub surface approaches
each other as the pair of side surfaces becomes closer to the
radial outer side in the direction of the axis, in a region on the
radial outer side.
4. The impeller according to claim 1, wherein the impeller body and
the blades are formed of a complex material consisting of a resin
and reinforcing fibers.
5. The impeller according to claim 4, wherein the reinforcing
fibers are disposed in the impeller body and the blades so as to
extend in a direction orthogonal to the hub surface.
6. A rotary machine comprising: the impeller according to claim 1;
and a rotating shaft that is attached to the impeller and rotates
together with the impeller.
7. The impeller according to claim 2, wherein each of the blades is
formed such that the pair of side surfaces in a cross-section along
the hub surface in a region close to the hub surface approaches
each other as the pair of side surfaces becomes closer to the
radial outer side in the direction of the axis, in a region on the
radial outer side.
8. The impeller according to claim 2, wherein the impeller body and
the blades are formed of a complex material consisting of a resin
and reinforcing fibers.
9. The impeller according to claim 3, wherein the impeller body and
the blades are formed of a complex material consisting of a resin
and reinforcing fibers.
10. A rotary machine comprising: the impeller according to claim 2;
and a rotating shaft that is attached to the impeller and rotates
together with the impeller.
11. A rotary machine comprising: the impeller according to claim 3;
and a rotating shaft that is attached to the impeller and rotates
together with the impeller.
12. A rotary machine comprising: the impeller according to claim 4;
and a rotating shaft that is attached to the impeller and rotates
together with the impeller.
13. A rotary machine comprising: the impeller according to claim 5;
and a rotating shaft that is attached to the impeller and rotates
together with the impeller.
Description
TECHNICAL FIELD
[0001] The invention relates to an impeller provided in a rotary
machine, and a rotary machine including an impeller.
[0002] Priority is claimed on Japanese Patent Application No.
2014-237695, filed Nov. 25, 2014, the content of which is
incorporated herein by reference.
BACKGROUND ART
[0003] While the global efforts of earth environment preservation
proceed, intensification of regulations regarding exhaust gas or
fuel efficiency in internal combustion engines, such as engines of
automobiles is under way. The turbochargers are rotary machines
that can enhance effects of fuel efficiency improvement and
CO.sub.2 reduction by sending compressed air into an engine to
combust fuel compared to natural intake engines.
[0004] In the turbochargers, a turbine is rotationally driven with
exhaust gas of an engine, thereby rotating an impeller of a
centrifugal compressor (for example, PTL 1). The air compressed by
the rotation of the impeller is raised in pressure by being reduced
in speed by a diffuser, and is supplied to the engine through a
scroll flow passage. In addition, as methods for driving the
turbochargers, not only methods of being driven with exhaust gas
but also, for example, methods using electric motors, methods using
prime movers, and the like are known.
[0005] If the impeller rotates, due to a centrifugal force of the
impeller, blades tend to be deformed toward a radial outer side,
and a centrifugal stress is generated. In order to reduce the
influence of such the centrifugal force, it is possible to make the
thickness of each blade small.
CITATION LIST
Patent Literature
[0006] [PTL 1] Japanese Unexamined Utility Model Registration
Application Publication No. H3-10040
SUMMARY OF INVENTION
Technical Problem
[0007] However, if the thickness of the blade is made small by
considering the influence of the centrifugal force, a bending
strength with respect to a pressure that a side surface (pressure
surface) of the blade receives from a fluid may decrease, and a
bending stress may increase.
[0008] The invention provides an impeller and a rotary machine
capable of reducing a centrifugal stress and a bending stress in a
well-balanced manner and improving strength.
Solution to Problem
[0009] According to a first aspect of the invention, an impeller
includes an impeller body forming a disk-like shape and rotating
about an axis together with a rotating shaft; and a plurality of
blades provided so as to protrude from a hub surface formed on a
front surface side of the impeller body, the blades each having a
pair of side surfaces that faces a circumferential direction of the
rotating shaft and allows a fluid to flow therealong. Each of the
blades is formed such that the pair of side surfaces in a
cross-section perpendicular to the axis approaches each other as
the pair of side surfaces becomes closer to a radial outer side of
the rotating shaft, at least within a range where stress in a
direction of the axis reaches a maximum.
[0010] According to such an impeller, the side surfaces of each of
the blades approach each other as the side surfaces become closer
to the radial outer side at least within the range where stress
reaches a maximum. Thus, the thickness of each of the blades
becomes small to the radial outer side. Therefore, the weight of
the blade can be reduced at a position (a position on a tip side)
on the radial outer side where the influence of a centrifugal force
becomes great. For this reason, the centrifugal stress at a
position (a position on the root side) on the radial inner side can
be reduced. Additionally, since the thickness of the blade becomes
large at a position on the root side compared to a position on the
tip side, a bending strength with respect to a pressure received
from a fluid is improved, and reduction of a bending stress at a
position on the root side is also possible.
[0011] According to a second aspect of the invention, in each of
the blades in the above first aspect, the pair of side surfaces in
a cross-section orthogonal to the axis is formed so as to be curved
in a concave shape in mutually approaching directions as the pair
of side surfaces becomes closer to a radial outer side and
approaches each other as the pair of side surfaces becomes closer
to the radial outer side.
[0012] Since the side surfaces of each of the blades are curved in
a concave shape in this way, the thickness of the blade can be made
small rapidly at a position on the tip side of the blade.
Additionally, the thickness of the blade can be made large rapidly
at a position on the root side of the blade. For this reason, the
centrifugal stress and the bending stress can be further
reduced.
[0013] According a third aspect of the invention, each of the
blades in the above first or second aspect may be formed such that
the pair of side surfaces in a cross-section along the hub surface
in a region close to the hub surface approaches each other as the
pair of side surfaces becomes closer to the radial outer side in
the direction of the axis, in a region on the radial outer
side.
[0014] Since the side surfaces of the blade approach each other as
the side surfaces become closer to the radial outer side in the
direction of the axis in a region on the radial outer side in the
blade in this way, the thickness of the blade becomes small from an
inlet side for a fluid toward an outlet side. Therefore, since the
gravity of the blade can be reduced at a position on the radial
outer side where the influence of a centrifugal force becomes
greater, a centrifugal stress generated in the blade can be further
reduced.
[0015] According to a fourth aspect of the invention, the impeller
body and the blades in any one of the above first to third aspects
may be formed of a complex material consisting of a resin and
reinforcing fibers.
[0016] The impeller formed of the complex material in this way has
a small density compared to a metallic impeller, the ratio of the
centrifugal stress to the bending stress becomes low, and the
magnitude of the bending stress and the magnitude of the
centrifugal stress are at an equal level. For this reason, if the
thickness of the blade is made small such that the centrifugal
stress is reduced, the bending stress increases even if the
centrifugal stress can be reduced. On the contrary, if the
thickness of the blade is made large such that the bending stress
is reduced, the centrifugal stress increases even if the bending
stress can be reduced. As a result, it is difficult to reduce the
stress generated in the blade as a whole. In this reason, since the
blade has a small thickness at a position on the tip side and the
thickness becomes large at a position on the root side, the
centrifugal stress and the bending stress can be reduced in a
well-balanced manner, and it is possible to reduce the stress
generated in the blade as a whole.
[0017] According to a fifth aspect of the invention, the
reinforcing fibers may be disposed in the impeller body and the
blades in the above fourth aspect so as to extend in a direction
orthogonal to the hub surface.
[0018] The bending stress and the centrifugal stress of the blade
are generated so as to run in the direction orthogonal to the hub
surface.
[0019] For this reason, such stresses can be effectively reduced by
disposing the reinforcing fibers in the direction in which these
stresses are generated.
[0020] Here, according to the aspect of the invention, the side
surfaces of the blade approach each other toward the radial outer
side. Thus, the thickness becomes small toward a position on the
radial outer side. For this reason, when the impeller of the
complex material is molded, a pressure loss occurs toward the
radial outer side in the direction of the axis. Therefore, the
resin in the complex material does not easily flow in this
direction. Therefore, during molding, the resin is made to flow in
the direction orthogonal to the hub surface. As a result, the
reinforcing fibers are naturally disposed so as to extend in the
direction orthogonal to the hub surface. Therefore, since the
impeller of the complex material is molded, a structure where
stress is naturally reduced can be provided.
[0021] According to a sixth aspect of the invention, a rotary
machine includes the impeller according to any one of the above
first to fifth aspects; and a rotating shaft that is attached to
the impeller and rotates together with the impeller.
[0022] According to such a rotary machine, the above impeller is
provided. Therefore, the side surfaces of each of the blades
approach each other as side surfaces become closer to the radial
outer side at least in the range where stress reaches a maximum.
Thus, the thickness of each of the blades becomes small to the
radial outer side. Therefore, since the gravity of the blade can be
reduced at a position on the radial outer side where the influence
of a centrifugal force becomes greater, a centrifugal stress at a
position on the root side of the blade can be further reduced.
Additionally, since the thickness of the blade becomes large at a
position on the root side compared to a position on the tip side, a
bending strength with respect to a pressure received from a fluid
is improved, and reduction of a bending stress at a position on the
root side is also possible.
Advantageous Effects of Invention
[0023] According to the above impeller and rotary machine, the
blades of which the thickness becomes small as they become closer
to the radial outer side of the rotating shaft. Thus, the
centrifugal stress and the bending stress are reduced in a
well-balanced manner, and an improvement in strength is
possible.
BRIEF DESCRIPTION OF DRAWINGS
[0024] FIG. 1 is a longitudinal sectional view illustrating a
turbocharger related to a first embodiment of the invention.
[0025] FIG. 2 is a longitudinal sectional view illustrating a
compressor impeller of the turbocharger related to the first
embodiment of the invention.
[0026] FIG. 3 is a view illustrating a meridian plane shape of a
blade of the compressor impeller of the turbocharger related to the
first embodiment of the invention, a horizontal axis represents
positions in a direction of an axis in the blade, and a vertical
axis represents positions in a radial direction of a rotating shaft
in the blade.
[0027] FIGS. 4A and 4B are longitudinal sectional views of a blade
of the compressor impeller of the turbocharger related to the first
embodiment of the invention. FIG. 4A illustrates an A-A section of
FIG. 3. FIG. 4B illustrates a B-B section of FIG. 3.
[0028] FIG. 5 is a view illustrating a meridian plane shape of a
blade of a compressor impeller of a turbocharger related to a
second embodiment of the invention, a horizontal axis represents
positions in the direction of the axis of the rotating shaft in the
blade, and a vertical axis represents positions in the radial
direction of the rotating shaft in the blade.
[0029] FIG. 6 is a view illustrating a cross-section along a hub
surface of the blade of the compressor impeller of the turbocharger
related to the second embodiment of the invention, and illustrating
a C-C section of FIG. 5.
[0030] FIG. 7 is a view illustrating an example of a sectional
shape along the hub surface of the blade of the compressor impeller
of the turbocharger related to the second embodiment of the
invention. A horizontal axis represents the distance from a fluid
inlet (leading edge) of the blade on the meridian plane. A vertical
axis represents ratios (blade thickness ratios: blade thickness
ratio in a case where a maximum value of blade thickness is set to
1.0) of the thickness of the blade.
DESCRIPTION OF EMBODIMENTS
First Embodiment
[0031] Hereinafter, a turbocharger 1 (rotary machine) related to an
embodiment of the invention will be described.
[0032] As illustrated in FIG. 1, the turbocharger 1 includes a
rotating shaft 2, a turbine 3 and a compressor 4 that rotate
together with the rotating shaft 2, and a housing coupling part 5
that couples the turbine 3 and the compressor 4 and supports the
rotating shaft 2.
[0033] In the turbocharger 1, a turbine 3 is rotated with exhaust
gas G from an engine (not illustrated), and air AR compressed by
the compressor 4 is supplied to the engine with the rotation.
[0034] The rotating shaft 2 extends in a direction of an axis O.
The rotating shaft 2 rotates about the axis O.
[0035] The turbine 3 is disposed on one side (the right side of
FIG. 1) in the direction of the axis O.
[0036] The turbine 3 includes a turbine impeller 14 that has the
rotating shaft 2 attached thereto and has a turbine blade 15, and a
turbine housing 11 that covers the turbine impeller 14 from an
outer peripheral side.
[0037] The rotating shaft 2 is fitted into the turbine impeller 14.
The turbine impeller 14 is rotatable around the axis O together
with the rotating shaft 2.
[0038] The turbine housing 11 covers the turbine impeller 14. A
scroll passage 12, which extending from a leading edge part (an end
part on a radial outer side) of the turbine blade 15 toward the
radial outer side, is formed in an annular shape about the axis O
at a position on the radial outer side, and allows the inside and
outside of the turbine housing 11 to communicate with each other
therethrough, is formed in the turbine housing 11. The turbine
impeller 14 and the rotating shaft 2 are rotated by the exhaust gas
G being introduced into the turbine impeller 14 from the scroll
passage 12.
[0039] Additionally, a discharge port 13 opening to one side of the
axis O is formed in the turbine housing 11. The exhaust gas G that
has passed through the turbine blade 15 flows toward one side of
the axis O, and is discharged from the discharge port 13 to the
outside of the turbine housing 11.
[0040] The compressor 4 is disposed on the other side (the left
side of FIG. 1) in the direction of the axis O.
[0041] The compressor 4 includes a compressor impeller 24 that has
the rotating shaft 2 attached thereto and has a compressor blade
25, and a compressor housing 21 that covers the compressor impeller
24 from the outer peripheral side.
[0042] The rotating shaft 2 is fitted into the compressor impeller
24. The compressor impeller 24 is rotatable around the axis O
together with the rotating shaft 2.
[0043] The compressor housing 21 covers the compressor impeller 24.
A suction port 23 opening to the other side of the axis O is formed
in the compressor housing 21. The air AR is introduced from the
outside of the compressor housing 21 through the suction port 23
into the compressor impeller 24. By a rotative force from the
turbine impeller 14 being transmitted to the compressor impeller 24
via the rotating shaft 2, the compressor impeller 24 rotates around
the axis O and the air AR is compressed.
[0044] A compressor passage 22, which extend from a trailing edge
part (a downstream end part of a flow of the air AR) of the
compressor blade 25 toward the radial outer side, forms an annular
shape about the axis O at a position on the radial outer side, and
allows the inside and outside of the compressor housing 21 to
communicate with each other therethrough, is formed in the
compressor housing 21. The air AR compressed by the compressor
impeller 24 is introduced to the compressor passage 22, and is
discharged to the outside of the compressor housing 21.
[0045] The housing coupling part 5 is disposed between the
compressor housing 21 and the turbine housing 11. The housing
coupling part 5 couples the compressor housing 21 and the turbine
housing 11. Moreover, the housing coupling part 5 covers the
rotating shaft 2 from the outer peripheral side, and the housing
coupling part 5 is provided with a bearing 6. The rotating shaft 2
is supported by the bearing 6 so as to be rotatable relative to the
housing coupling part 5.
[0046] Next, the compressor impeller 24 will be described in detail
with reference to FIG. 2.
[0047] The compressor impeller 24 includes a plurality of the
compressor blades 25, and an impeller body 31 that supports the
compressor blades 25 on the other side of the axis O that becomes a
front surface side.
[0048] The impeller body 31 has a disk-like shape. The impeller
body 31 is a so-called hub formed of a complex material consisting
of a resin and reinforcing fibers.
[0049] Here, as resins used for the impeller body 31, polyether
sulfone (PES), polyether imide (PEI), polyether ether ketone
(PEEK), polyether ketone (PEK), polyether ketone ketone (PEKK) and
poly ketone sulfide (PKS), polyaryl ether ketone (PAEK), aromatic
polyamide (PA), polyamide imide (PAI), polyimide (PI), and the like
are exemplified.
[0050] Additionally, as the reinforcing fibers used for the
impeller body 31, carbon fibers, glass fibers, Whisker, and the
like are exemplified.
[0051] A boss hole section 31a having the rotating shaft 2 inserted
therethrough and fitted thereinto is formed in a region on a radial
inner side in the impeller body 31. A surface formed on the front
surface side of the impeller body 31 is a hub surface 31b formed so
as to be inclined toward the radial outer side as it becomes closer
to one side in the direction of the axis O.
[0052] The compressor blades 25 are formed of a complex material
consisting of the same resin and reinforcing fibers as that the
impeller body 31. The compressor blades 25 are provided so as to
protrude from the hub surface 31b integrally with the impeller body
31.
[0053] As illustrated in FIGS. 2 to 4B, each of the compressor
blades 25 has a pair of side surfaces 26 that faces a
circumferential direction of the rotating shaft 2 and allows air
(fluid) A to flow therealong. One of the pair of side surfaces 26
is a pressure surface that receives the pressure of air. The other
of the pair of side surfaces 26 is a negative pressure surface.
[0054] The plurality of compressor blades 25 are provided apart
from each other in the circumferential direction. A flow passage FC
through which air AR flows is formed between side surfaces 26 that
face each other in two compressor blades 25 adjacent to each other
in the circumferential direction.
[0055] In the present embodiment, as the compressor blades 25, a
long blade 25A extending from the other side (the front surface
side of the impeller body 31) in the direction of the axis O in the
hub surface 31b, and a short blade 25B extending from one side
(back surface side of the impeller body 31) in the direction of the
axis O more than the long blade 25A in the hub surface 31b are
provided alternately in the circumferential direction.
[0056] As illustrated in FIGS. 3 and 4, each compressor blade 25 is
formed such that the pair of side surfaces 26 in a cross-section
orthogonal to the axis O approaches each other as it becomes closer
to the radial outer side of the rotating shaft 2. That is, the
thickness of the compressor blade 25 becomes small toward the
radial outer side.
[0057] In the compressor blade 25 of the present embodiment, the
pair of side surfaces 26 is curved in a concave shape in mutually
approaching directions as it becomes closer to the radial outer
side.
[0058] In the compressor blade 25 of the present embodiment, the
reinforcing fibers are disposed so as to extend in the direction
orthogonal to the hub surface 31b. That is, the direction of the
reinforcing fibers runs in a normal direction of the hub surface
31b (a direction of a two-dot chain line of FIG. 3).
[0059] According to the turbocharger 1 of the present embodiment
described above, the thickness of the compressor blade 25 becomes
small toward the radial outer side. Therefore, the weight of the
compressor blade 25 can be reduced at a position (a position on a
tip side) on the radial outer side where the influence of a
centrifugal force becomes greater. For this reason, a centrifugal
stress generated in the compressor blade 25 at the position (a
position on a root side) on the radial inner side connected with
the hub surface 31b side can be reduced. In addition, this
centrifugal stress is a tensile stress generated such that the
compressor blade 25 is pulled in the normal direction of the hub
surface 31b.
[0060] In the compressor blade 25, the thickness thereof becomes
large at a position on the root side compared to a position on the
radial outer side that becomes the tip side. For this reason, a
bending strength with respect to a pressure (a force acting on the
side surface 26 that is the pressure surface) received from the air
AR is improved, and reduction of a bending stress at a position on
the root side is also possible.
[0061] Moreover, in the present embodiment, the pair of side
surfaces 26 in the compressor blade 25 is curved in a concave
shape. Thus, the thickness of the compressor blade 25 can be made
small rapidly at a position on the tip side of the compressor blade
25. Additionally, the thickness can be made large rapidly at a
position on the root side of the compressor blade 25. For this
reason, the centrifugal stress and the bending stress can be
further reduced.
[0062] Additionally, in the present embodiment, the compressor
impeller 24 is formed of a complex material.
[0063] Here, the impeller of the complex material has a small
density compared to a metallic impeller, the ratio of the
centrifugal stress to the bending stress becomes low, and the
magnitude of the bending stress and the magnitude of the
centrifugal stress are at an equal level. For this reason, if the
thickness of the blade is made small such that the centrifugal
stress is reduced, the bending stress increases even if the
centrifugal stress can be reduced. On the contrary, if the
thickness of the blade is made large such that the bending stress
is reduced, the centrifugal stress increases even if the bending
stress can be reduced. As a result, it is difficult to reduce both
the centrifugal stress and the bending stress to reduce the stress
generated in the blade as a whole.
[0064] In this regard, the compressor blade 25 of the present
embodiment has a small thickness at a position on the tip side and
has a large thickness at a position on the root side. For this
reason, the centrifugal stress and the bending stress can be
reduced in a well-balanced manner, and it is possible to reduce the
stress generated in the compressor blade 25 as a whole.
[0065] In the compressor blade 25, the reinforcing fibers are
disposed so as to extend in the direction orthogonal to the hub
surface 31b. Here, the bending stress and the centrifugal stress of
the compressor blade 25 are generated so as to run in the direction
orthogonal to the hub surface 31b, that is, the normal direction of
the hub surface 31b. In the present embodiment, such stresses can
be effectively reduced by disposing the reinforcing fibers in the
direction in which these stresses are generated.
[0066] Here, in the present embodiment, the pair of side surfaces
26 of each compressor blade 25 approaches each other toward the
radial outer side. Thus, the thickness becomes small toward a
position on the radial outer side in a cross-section orthogonal to
the axis O. For this reason, when the compressor impeller 24 of the
complex material is molded, a pressure loss occurs toward the
radial outer side in the direction of the axis O.
[0067] As a result, the resin in the complex material does not
easily flow in this direction. Therefore, during molding, the resin
is made to flow in the direction orthogonal to the hub surface 31b,
the reinforcing fibers are naturally disposed so as to extend in
the direction orthogonal to the hub surface 31b, and the compressor
impeller 24 of the complex material is molded. Thus, it is possible
to provide a structure where stress is naturally reduced during
molding.
[0068] Here, the compressor blade 25 of the present embodiment has
only to be formed into a tapered shape such that the side surfaces
26 approach each other like as it becomes closer to the radial
outer side as described above, in a range where at least the stress
in the direction of the axis O of the rotating shaft 2 acquired in
advance reaches a maximum. That is, the compressor blade 25 may not
have the tapered shape in this way in the whole region in the
direction of the axis O.
Second Embodiment
[0069] Next, a second embodiment of the invention will be described
with reference to FIGS. 5 to 7.
[0070] The same constituent elements as those of the first
embodiment will be designated by the same reference signs, and the
detailed description thereof will be omitted.
[0071] The turbocharger 50 of the present embodiment is different
from the first embodiment in the shape of compressor blades 52 in a
compressor impeller 51.
[0072] Namely, each compressor blade 52 of the present embodiment,
similar to each compressor blade 25 of the first embodiment, are
formed such that a shape of a cross-section (a cross-section in the
radial direction) orthogonal to the axis O is formed into a tapered
shape, and additionally, a pair of side surfaces 56 in a
cross-section along the hub surface 31b approaches each other as it
becomes closer to the radial outer side in the direction of the
axis O in a region (a region including a position connected to the
hub surface 31b) close to the hub surface 31b a region on the
radial outer side.
[0073] In more detail, as illustrated in FIG. 6, in the present
embodiment, each of the pair of side surfaces 56 has a leading edge
side surface 57 formed in a region closer to the other side (the
front surface side of the impeller body 31) in the direction of the
axis O than a halfway position M in the direction of the axis O
from a leading edge end of the compressor blade 52 along a meridian
plane of the compressor blade 52, and a trailing edge side surface
58 formed in a region up to a trailing edge end of the compressor
blade 52, continuously with the leading edge side surface 57.
[0074] The leading edge side surfaces 57 in the pair of side
surfaces 56 are formed being curved in a convex shape so as to be
spaced apart from each other in the circumferential direction.
[0075] The trailing edge side surfaces 58 in the pair of side
surfaces 56 are continuous with the leading edge side surfaces 57,
respectively, and are curved and formed in a concave shape such
that the compressor blade 52 has a tapered shape along the meridian
plane by approaching each other in the circumferential
direction.
[0076] According to the turbocharger 50 of the present embodiment
described above, the trailing edge side surfaces 58 are formed in
the regions on the radial outer side in the compressor blade 52.
Thus, the side surfaces 56 approach each other as they become
closer to the radial outer side along the meridian plane of the
compressor impeller 51 in the direction of the axis O. For this
reason, the thickness of the compressor blade 52 becomes small
toward the radial outer side, and the gravity of the compressor
blade 52 can be reduced at a position on the radial outer side
where the influence of a centrifugal force becomes larger.
Therefore, the centrifugal stress at a position on the root side of
the compressor blade 52 can be further reduced.
[0077] Moreover, in the present embodiment, the trailing edge side
surfaces 58 are curved in a concave shape. Thus, the thickness of
the compressor blade 52 becomes small rapidly.
[0078] Namely, compared to a case where the trailing edge side
surfaces 58 in the pair of side surfaces 56, similar to the leading
edge side surfaces 57, are curved and formed in a convex shape so
as to be spaced apart from each other in the circumferential
direction as illustrated by a dashed line X of FIG. 7, the
thickness of the compressor blade 52 becomes small rapidly from the
above halfway position as illustrated by a solid line Y of FIG. 7,
in the case of the present embodiment.
[0079] Therefore, the centrifugal stress and the bending stress
generated in the compressor blade 52 can be further reduced.
[0080] Here, the pair of trailing edge side surfaces 58 in each
compressor blade 52 of the present embodiment are not limited to a
case where the trailing edge side surfaces are curved in a concave
shape, and may be provided so as to approach each other as it
extends linearly and becomes closer to the radial outer side (refer
to a two-dot chain line Z of FIG. 6). Namely, the compressor blade
52 has only to have at least a tapered shape toward the trailing
edge side.
[0081] Although the embodiments of the invention have been
described above in detail, some design changes can also be made
without departing from the technical idea of the invention.
[0082] For example, the compressor impellers 24 and 51 are not
limited to a case where the compressor impellers are made of the
complex material, and may be made of a metal.
[0083] Additionally, in a case where the compressor blades 25 and
52 are formed of the complex material, the direction in which the
reinforcing fibers extend is not limited to a direction orthogonal
to the hub surface 31b.
[0084] Additionally, the pair of side surfaces 26 in each of the
compressor blades 25 and 52 are not limited to a case where the
side surfaces are curved in a concave shape, and may be provided so
as to approach each other as it extends linearly and becomes closer
to the radial outer side (refer to a two-dot chain line L of FIG.
4).
[0085] Additionally, in the above-described embodiments, as the
rotary machine, the turbocharger has been described as an example.
However, the invention may be used for other centrifugal
compressors and the like.
INDUSTRIAL APPLICABILITY
[0086] According to the above impeller and rotary machine, the
blades of which the thickness becomes small as they become closer
to the radial outer side of the rotating shaft. Thus, the
centrifugal stress and the bending stress are reduced in a
well-balanced manner, and an improvement in strength is
possible.
REFERENCE SIGNS LIST
[0087] 1: TURBOCHARGER (ROTARY MACHINE) [0088] 2: ROTATING SHAFT
[0089] 3: TURBINE [0090] 4: COMPRESSOR [0091] 5: HOUSING COUPLING
PART [0092] 6: BEARING [0093] 11: TURBINE HOUSING [0094] 12: SCROLL
PASSAGE [0095] 13: DISCHARGE PORT [0096] 14: TURBINE IMPELLER
[0097] 15: TURBINE BLADE [0098] 21: COMPRESSOR HOUSING [0099] 22:
COMPRESSOR PASSAGE [0100] 23: SUCTION PORT [0101] 24: COMPRESSOR
IMPELLER [0102] 25: COMPRESSOR BLADE [0103] 25A: LONG BLADE [0104]
25B: SHORT BLADE [0105] 26: SIDE SURFACE [0106] 31: IMPELLER BODY
[0107] 31a: BOSS HOLE SECTION [0108] 31b: HUB SURFACE [0109] G:
EXHAUST GAS [0110] AR: AIR [0111] O: AXIS [0112] FC: FLOW PASSAGE
[0113] 50: TURBOCHARGER (ROTARY MACHINE) [0114] 51: COMPRESSOR
IMPELLER [0115] 52: COMPRESSOR BLADE [0116] 56: SIDE SURFACE [0117]
57: LEADING EDGE SIDE SURFACE [0118] 58: TRAILING EDGE SIDE
SURFACE
* * * * *